On thefxed Oil bf Wine, l^c. 209 



triclty, has given it as his opinion that bodies equally electrified 

 recede from each other, being attracted by the surrounding air. 

 But as my experiments were made before I saw his work, and 

 they do not appear to interfere with his observations, it may not 

 be considered presumptuous in offering them to your notice. 



When two balls are electrified positive! v, the air intervening 

 between them, receiving a portion of the fluid from each of the 

 balls, becomes so highly electrified positively, that the external 

 air is comparatively electrified ne(;atively ; consequently the mu- 

 tual attraction between the air and balls being greatest in the op- 

 posite directiojis *, the balls will recede from each other, being 

 oppositely attracted. 



Were tiie divergence caused by the attraction of the surround- 

 ing air, the balls should not recede when electrified in vacuo ; 

 whereas if it be the effect of electrical repulsion, the balls should 

 recede still more in vacuo, the resistance being lessened. 



To ascertain this, I used an air-pump with a glass plate, and 

 suspended two small pith balls from a wire passing through the 

 centre of a large receiver. 



When the receiver was partly exhausted, I electrified the balls, 

 and found the divergence was considerably lessened : but when 

 completely exhausted, there was not the slightest motion percep- 

 tible in the balls, although several successive sparks were com- 

 municated from a Leyden jar. 



I then suspended the balls much nearer one side of the re- 

 ceiver than the other : and when electrified in vacuo, the result 

 was, that they were both equally attracted towards the nearest 

 side of the receiver. • 



It therefore appears to me that we are justified in concluding 

 that the recession of bodies et|ually electrified is caused by the 

 attraction of the surrounding air : and certainly this hypothesis 

 is the most simple, and most congenial to the maxim — that we 

 should never bring two principles into action when only one is 

 necessary. I am, sir, yours, &c. 



W. 



LV. On the " Fixed Oil of Wine;" and on the Light emitted ly 

 metallic Wires of low Temperature in certain volatile Media. 

 By Mr. J. Farlev. 



J To Mr. Tilloch. 



Sir, — J-T was my intention (at no distant period) to have trou- 

 bled you with an account of a few experiments for insertion in your 



* It is well known, that a body positively electrified will have a greater 

 attraction for another body, in proportion us the other body is negatively 

 elnctrifit'd. 



Vol.49, No.227.iWarcA 1817. O Maga- 



